1. Field of the Invention
The present invention relates to an electronic paper display device and a manufacturing method thereof, and more particularly, to an electronic paper display device that has cells defined by a barrier and electronic balls disposed in the respective cells, and a manufacturing method thereof.
2. Description of the Related Art
As a next generation display device, a liquid crystal display (LCD), a plasma display panel (PDP), an electroluminescence, an electronic paper display device, etc. have been widely spread.
Among others, the electronic paper display device is flexibly bendable and is much cheaper than other display devices in view of its production costs.
Further, the electronic paper display device does not need a background illumination or a continuous recharging so that it can be driven with very little energy, having significantly excellent characteristics in energy efficiency.
Moreover, the electronic paper display device is clear and has a wide viewing angle, and is also able to have a memory function that displayed characters or images do not completely disappear even though power is instantly blocked. Therefore, the electronic paper display device has been expected to be widely used in a foldable screen, an electronic wallpaper, etc. as well as print media such as books, newspapers or magazines.
Meanwhile, technical schemes capable of implementing the electronic paper display device have been largely divided into a scheme using a liquid crystal, an organic EL scheme, a reflection film reflective display scheme, an electrophoretic scheme, a twist ball scheme, an electrochromic scheme, a mechanical reflective display scheme, etc. and have been developed.
Among others, the electronic paper display device using the twist balls includes two electrodes and an elastomer sheet that is interposed between the two electrodes and to which the twist balls having an optical and electrical anisotropy are attached. At this time, dielectric liquid is coated on an outer circumferential surface of the twist ball. Herein, the twist ball may be configured of a black hemisphere and a white hemisphere that are charged with different charges. With the electronic paper display device using such a twist ball, when voltage is applied to the two electrodes, the respective hemispheres of particles are rotated to face the electrode surfaces of polarities opposite to each other inside the dielectric liquid according to the applied voltage direction, thereby displaying black and white.
At this time, since the twist balls are attached onto the elastomer sheet, the twist balls are not uniformly arranged on the elastomer sheet and partial regions where the twist balls are overlapped with each other or not arranged are generated, causing a problem that the contrast ratio of the electronic paper display device is degraded.
Therefore, the electronic paper display device using the twist balls in the related art has problems that the contrast ratio is degraded or image quality defects are caused due to the degradation of the uniformity in the arrangement of the twist balls.